The German patent publication DE 10 2006 041 981 A1 relates to an electric machine. The electric machine relates particularly to an electrically excited claw-pole generator for a motor vehicle. The claw-pole generator comprises a rotor having a plurality of axially oriented poles which alternate magnetization in the peripheral direction and permanent magnets disposed between the poles for increasing performance and reducing the magnetic leakage flux. The permanent magnets are secured by means of non-magnetic plates bilaterally held in pole grooves. These plates comprise in each case at least one additional locking mechanism with which they are supported in the axial direction at the poles. The additional locking mechanisms are, for example, designed as sheet metal tabs which are bent or angled and are supported in a resiliently clamping manner at least one axial end section of the poles.
The German patent publication DE 199 51 115 A1 likewise relates to an electric machine. This electric machine relates to a generator for a motor vehicle having an exciter system and a plurality of electrically excited salient poles in the stator or rotor. The stator as well as the rotor thereby comprises the form of electromagnetically excited poles which are axially oriented on the periphery and are alternatively polarized in the peripheral direction. In order to reduce magnetic leakage flux, permanent magnets are situated in the interstices between the poles. The permanent magnets are inserted into the aforementioned interstices. Said permanent magnets on the stator, respectively the rotor, are secured in such a way that they are in each case held by means of a magnetically non-excitable holding element. This holding element is bilaterally mounted in pole grooves in the tangential and axial directions by means of caulking; and a pole groove is longitudinally incorporated into one pole and a pole groove is longitudinally incorporated into an opposite pole. In the case of a rotor, the holding element covers the respective permanent magnet in the radial direction to the stator or in the case of a stator in the radial direction to the rotor with a base section. Bent tabs, which exert a clamping force on axial front faces of the inserted permanent magnets, are located at each of the opposite ends of the base section.
In the case of electric machines as those known from the German patent publications DE 19 2006 041 981 A1 and DE 199 51 115 A1, the claw poles of a claw-pole machine tend to bend up radially outwards at high rotational speeds >20,000 rpm. This deformation occurs more or less dramatically, in each case depending on the rotational speed of the electric machine.